Questions tagged [functions]
Questions about the use of built-in Mathematica functions, including pure functions.
3
votes
2answers
114 views
Print characters from list with a For-loop
Suppose I have the list
primary = {"b","a","e"}
I want to get the following output with a For-loop (or While-loop)
"b"
"a"
"e"
My code is:
...
2
votes
1answer
85 views
What is FindFormula returning?
I was playing around with FindFormula and am experiencing some odd behavior.
I am running MMA 12.0.0.0 on a Windows 10, x86 architecture - if that matters.
...
0
votes
1answer
36 views
How to create a list of undefined functions?
I have a undefined function $\phi[i,j]$ where $i=0,1,...,m$ and $i=0,1,...,n$.
How can I generate this list:
{$\phi[0,0],\phi[1,0],...,\phi[m,0],\phi[0,1],\phi[1,1],...\phi[m,1],\phi[0,2],...,\phi[m,...
0
votes
0answers
26 views
How to graph a text as a function of some arbitrary parameters?
I'm trying to graph a text in a couple of plots I have. I want to be able to edit the text depending on the values I choose (rho0, zp, zm, temp, ion, and perm) and show them at some point in my plot (...
1
vote
1answer
40 views
InverseFunction never stops running
I have a problem finding the inverse of a function, perhaps I'm missing something.. I'd appreciate it if someone can help me out.
First, I calculate an Integral of the form
...
0
votes
0answers
49 views
How to solve “Coordinate should be a triple of numbers”?
Something seems different with duplicated question "How to solve this error? “should be a triple of numbers or a Scaled form.”
", MMA tips may tell that Abs do not ...
0
votes
0answers
38 views
Saving remembered function when closing down notebook [duplicate]
I have functions defined to remember their values
f[x_]:=f[x]
I would like to be able to close a notebook without losing the computed values, what is the ...
0
votes
0answers
52 views
Why can $ 0.i$ appear? [closed]
I have some function f[x_] which returns NUMBER + 0.i for any x. Is there a reason that Mathematica displays + 0.i summand? How to avoid it without taking Re[]?
2
votes
0answers
28 views
Issue passing a list to last argument of ImplicitRegion (Scope issue?) [duplicate]
This is a very strange issue I'm having trying to pass a list as an argument to Mathematica's "ImplicitRegion" function. Here's the issue:
...
0
votes
0answers
27 views
How to find a domain at which a function is non-zero
Consider some function f[x,y]. Is there any way to find a domain at which it is non-zero?
Namely, I would like to compute the integral
...
0
votes
0answers
33 views
Defining a function through an ODE containing unspecified operators
I want to do some algebra using a function only defined through a DE containing unspecified operators. The DE is
$$
\partial_zu(z) = \left[\hat{D}+\hat{N}(z,u)\right] u(z).
$$
Here $u$ lives in ...
0
votes
1answer
74 views
Part assignment is not a symbol [duplicate]
read some related posts and found no solution. For a list defined like this
m = {0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.9, 1.0, 1.5, 1.6};
when I define this function
...
1
vote
1answer
48 views
Where does Wolfram publish an index of built-in functions on the web? [duplicate]
Where is a online reference for the built-in functions of Mathematica/Wolfram?
0
votes
1answer
47 views
Strange result of MatrixFunction
Let us consider the sum of the matrix series
m = 2; n = 3; Sum[MatrixPower[{{1, 2}, {3, 4}}, m + k*n]/(m + n*k)!, {k, 0, Infinity}]
{{-(32 E^(-(5/4) - Sqrt[33]/...
2
votes
0answers
90 views
Why was implementation of “Exponent” changed since version 11.3? [closed]
I have a following expression and need an exponent of n
Exponent[Exp[Sqrt[n]]*n^2, n]
(* 2 *)
Exponent[Exp[Sqrt[n]]*n, n]
(* 1 *)
All versions 7,8,9,10 up ...
0
votes
0answers
47 views
How to exclude some methods?
Can I exclude one or several methods from methods tried by a function?
When we use some 'algorithm-intensive' function, we can often specify whether we want to proceed according to the chosen method ...
1
vote
0answers
43 views
Force FindFormula to avoid Piecewise in the result?
Is it possible to provide any arguments to FindFormula to force it to avoid using Piecewise in the result, but instead try to ...
0
votes
1answer
74 views
Arrays, Mapping, and Convolutions
I'm trying to create a function that convolutes a 3D Normal Distribution to the points listed below. However, I think I'm going about it in the wrong way.
When I try and convolve it with the points, ...
2
votes
1answer
77 views
Switch Function Is Not Working Properly
I'd like to select between the Tent and Hat function to convolve, but my switch function produces an error.
I don't exactly need the initial plots. But I would like to plot the two that I select.
<...
0
votes
1answer
47 views
Definition of complex conjugate?
I came across the following way of defining complex conjugate in mathematica [a]:
SuperStar[y_] := y /. Complex[u_, v_] -> Complex[u, -v]
I am able to ...
2
votes
3answers
68 views
Creating a function that can be used to plot a triangle with an area of 1
The function should take an input x, which is the absolute value of the bounds of the triangle and should be centered at 0.
I'd like to use ...
0
votes
1answer
37 views
Finding the negative real root of in set of solutions under a varying constraint
Suppose I have a function and its derivative like:
V = x^3.5 - x*y
Vx = D[V, x]
I first solve V for ...
0
votes
1answer
55 views
How can I protect all possible function names?
It is possible to protect all possible function names?
All functions have Attributes, e.g.
Attributes[Plus]
will give
<...
0
votes
0answers
12 views
Operating functions with two arguments? [duplicate]
Let us first consider function with single argument.
f1[x_] := x^2
The value of function at any value of $x$, for example, $x=3$ can be evaluated with any of the ...
0
votes
0answers
22 views
Redefining the inbuilt function and its derivative [duplicate]
I want to redefine the DiracDelta functions and its derivatives. I am successful at redefining the DiracDelta function but not ...
0
votes
2answers
108 views
Mathematica puts function with certain constants on hold, why? [closed]
Here, I probably have a trivial case on how to use functions in Mathematica but I can't figure it out with the help of the Mathematica pages. I define the following function:
...
4
votes
4answers
360 views
Applying a function to a nested list
Say I have a list:
l = {{{a, b}, c}, d}
I now want to apply a function, call it F to that list in a way that I go from the ...
1
vote
1answer
59 views
Plotting $f: x + i\,y \mapsto u + i\, v$ with Plot3D and mapping $v$ to color
Mathematica already has ComplexPlot3D that plots ReIm[x, y] against Abs[f(z)] and ...
0
votes
0answers
53 views
Function for Probability of k Successes, Given Probability Vector [closed]
In an earlier post, @gwr provided the following function for a Poisson Binomial Distribution:
...
1
vote
2answers
49 views
Matrix whose coefficients are functions
What is the right way to declare of matrix whose coefficients are functions of a variable $x$ ?
I tried :
Table[Table[a[i,j][x_],{j,1,NN}],{i,1,NN}]
1
vote
4answers
125 views
Compute “most-occuring weekdays” function
I am attempting to solve the Most-Occurring Weekdays in a Year challenge to teach myself Mathematica.
Specifically, the challenge is:
Write a function MostOccurringWeekday that takes an integer ...
0
votes
0answers
43 views
How to handle exceptions and failures in Mathematica?
In python I can write fallback values like:
...
4
votes
3answers
118 views
Find and load all ResourceFunctions as top level functions?
I would like to be able to use ResourceFunction's as top-level symbols:
The reason being that some of them are so useful it would be really great not to have to ...
0
votes
1answer
39 views
Function that refuses to return a value
I wanted to know the exact solution to the following differential equation
$$
\frac{\mathrm{d}^2 y}{\mathrm{d} t^2} = - \frac{1}{y-1}, \quad \begin{aligned} y(0) &= 0 \\ \left. \frac{\mathrm{d} y}...
0
votes
0answers
52 views
Plot BV functions with singular derivatives in multiple space dimension
In 1-dimensional setting, two key examples of $BV$ functions (of bounded variation) $u: \mathbb R \to \mathbb R$ are the Heaviside function, whose derivative is the Dirac delta concentrated at $0$. It ...
0
votes
0answers
84 views
Is it possible to find the Rössler attractor using only a set of Lyapunov exponents?
Is it possible to use a set of Lyapunov exponents to determine the orbits of the Rössler system? If so, could how would I go about plotting them?
EG.
Known
Unknown
0
votes
1answer
54 views
Returning a string from a piecewise function
I need to define a function that behaves as a piecewise function, but will return a string instead of a value. Part of the function that I have written is provided below. The full function continues ...
0
votes
0answers
23 views
Find a reduce math function with increase param value [migrated]
I have a d value which is a range from 0->5. I want to build a math function with d param so that return a value from 0 to 1. if d increase, function decrease faster. Example f (d = 0) = 1, f (d = 1) =...
3
votes
2answers
65 views
Function to join variable names
I am trying to define a function that takes any two strings (possibly predefined as variables, functions, etc.) and join them in one string (which can also be predefined and will keep its definition ...
0
votes
1answer
26 views
5
votes
1answer
102 views
Which version of Mathematica did DiracDelta become to the derivative of HeavisideTheta from that of UnitStep?
The mathematica's version of my coworkers is 5.0, they use UnitStep to derive formula, However, I also want to use the parallel features so used the latest version ...
0
votes
5answers
79 views
Sum Over Solutions to an Equation
Two Related Questions
Is there any general built-in functionality for computing a sum over solutions to an equation? This is common in number theory. For example, computing sums of the following form....
0
votes
1answer
49 views
Recursive Function in Multiple Variables
I can define a recursive function in one variable, e.g. defining the factorial function $f(n)= n!$ using Mathematica. But how do you do this for a function which depends not only on $n$ but on $x$ and ...
1
vote
1answer
43 views
Verifying which 5-strings form valid words
words = getWordsFromPi[200];
For[i = 0, i < Length[words], i++,
if[DictionaryWordQ[StringJoin[words[[i]]],
Insert[list, words[[i]]]]]]
...
1
vote
0answers
26 views
Finding the positions of minima for a function with algebraic constants
I have a function of several variables:
inverse[Qx_, Qy_]:= T - 2 J + 4 J1 Cos[(Qx + Qy)/2 a] Cos[(Qx - Qy)/2 a] - 2 J2 Cos[(Qx - Qy) a] + 2 J3 Cos[(Qx + Qy) a]
...
0
votes
0answers
17 views
Unclear behaviour of Position, lists and functions in general [duplicate]
apologies for the title, but I have such a confusion about my question that I haven't been able to formalise a clear title.
My question arise from the "discrepancy" between the results of the ...
0
votes
1answer
35 views
How to plot two functions together when one of them needs to be a series of dots, with common labels and colors?
I have two functions that I want to plot together. I want to plot the non-linear and the linear (NL and L in my code) functions together, but I wish that the NL function is plotted as a series of dots ...
11
votes
2answers
394 views
0
votes
2answers
77 views
Problem with a simple recursive function
f[2 x_] := f[x]
f[1] := 3
f[0] := 0
f[2 x_ + 1] := f[x] + f[x + 1]
a[x_] := f[x]/f[x + 1]
Will this work as an recursive function ?
I think there's something ...
0
votes
0answers
56 views
